Going forward, the two senators are bound to part company on the debt and spending showdowns, leaving Landrieu exposed the more she votes with fellow Democrats and President Barack Obama. She could draw the line against possible Democratic proposals to end energy industry tax breaks. Beyond that, her best hope could lie in another bipartisan gang of however many emerging to offer a middle position and to give her some separation from the president.

Vitter's cliff vote also was interesting because he stayed solidly within the fold of GOP senators. There was a time when he may easily have joined the GOP dissidents. In 2008, he was among the first Republican senators to break with the Bush administration by speaking out against the Wall Street and General Motors bailouts, as though he could see the tea party of 2010 coming.

Now he has chosen to be a team player, as he becomes the ranking member of the Environment and Public Works Committee and the newly chosen deputy whip. Even while taking the hard party line against the Democrats on big fiscal issues, he will continue to develop a bipartisan working relationship with his committee chairwoman, Sen. Barbara Boxer of California, in fashioning big infrastructure spending bills. Vitter will be pressing for entitlement reform while doing all he can to steer more money back home for flood control projects, port improvements and the next highway bill.